They have said Mr Humala might try to build on the base of support he has among Peru's poor and a growing disenchantment with free market policies.

During the campaign he had the support of Venezuelan President Hugo Chavez, and many feared his election would further Mr Chavez's nationalist sphere of influence in Latin America, the BBC's Hannah Hennessy in Lima reports.

But Mr Humala said he had not spoken with Mr Chavez since the elections and insisted he would lead a democratic opposition.

However, he refused to rule out street protests if, as he said, the political reality demanded it.